Justin

Right, the way i understand it the groups move so the differences between diagrams can be a function of focal length differences. I am certain this lens gets the IS treatment. just hope it gets announced in early Jan like the 70-200 did.

Justin

However, the optical system is considerably complicated. A lens behind is fixed, but the other lenses move by focusing and zooming. The Cam will become the considerably elaborate mechanism. The body tube must upsize.

Translation?

Sounds like a potential description of an IS "mechanism". Certainly an extending lens.